http://www.histopathology-india.MelanocyticTumours.htm

Desmoplastic Spitz nevus (DSN) is a rare variant of spitzoid tumours characterized by dermal proliferation of large epitheliod and/or fusiform melanocytes within a desmoplastic stroma, comprising thick, eosinophilic collagen bundles.

Desmoplastic Spitz naevus (DSN) was first described by Reed et al. in 1975

It has clinical and histopathological features that are difficult to differentiate from dermatofibroma and desmoplastic malignant melanoma (DMM), which requires aggressive therapy for cure.

Images of Desmoplastic Spitz Nevus

It occurs most frequently in young adults and children

It is usually a red-brown papule or nodule, located on the extremities. However, lesions located on the abdomen, head and neck region and a case with multiple lesions have been reported 

Differential diagnosis:

Spitz naevus:  It is differentiated from classical variants of Spitz naevi by lack of dermoepidermal activity, absence of Kamino bodies, increased dermal collagen and presence of ganglion-like epithelioid cells.

Dermatofibroma:  The DSN can be mistaken for dermatofibroma due to similar location and clinical appearance. It can be differentiated precisely from dermatofibroma with the presence of melanocytes and the positive immunohistochemical staining of the cells with S-100 protein and antibody HMB-45.

Desmoplastic malignant melanoma:   From a histopathological point of view, symmetry, circumscription, melanocytic maturation and involvement of adnexal structure are significantly more frequent in desmoplastic Spitz nevi. The presence of melanocytic junctional nests associated with discohesive cells, variations in size and shape of the nests, lentiginous melanocytic proliferation, actinic elastosis, pagetoid spread, dermal mitosis, perineural involvement and brisk inflammatory infiltrate are significantly more frequent in desmoplastic melanoma. No significant difference is found concerning epidermal hyperplasia, presence of Kamino bodies or moderate inflammatory infiltrate.

Fluorescence in situ hybridization as an ancillary method for the distinction of desmoplastic melanomas from sclerosing melanocytic nevi.J Cutan Pathol. 2011 Apr;38(4):329-34. 

Desmoplastic nevus: An entity distinct from spitz nevus and blue nevus. Am J Dermatopathol. 2011 Feb;33(1):35-9.

Desmoplastic spitz naevus can be mistaken for desmoplastic malignant melanoma and dermatofibromaActa Derm Venereol. 2011 Jan;91(1):74-5

Desmoplastic Spitz nevus: a histopathological review and comparison with desmoplastic melanoma.Ann Dermatol Venereol. 2009 Oct;136(10):689-95

p16 expression differentiates between desmoplastic Spitz nevus and desmoplastic melanoma.J Cutan Pathol. 2009 Jul;36(7):753-9

Desmoplastic Spitz nevus showing vascular proliferation more prominently in the deep portion.Am J Dermatopathol. 2002 Apr;24(2):184-5.

Ancient Naevus  
Halo naevus
Balloon cell naevus  
Combined Naevus
Recurrent melanocytic naevus
                   
2. Spindle and epithelioid cell naevi

Spitz naevus
Pigmented spindle cell naevus

3. Blue naevi

Common blue naevus 
Cellular blue naevus

4. Dermal melanocytoses

Naevus of Ota
Naevus of Ito  
Mongolian spot  

5. Congenital melanocytic naevi                                            
6. Dysplastic melanocytic naevi